Valve system and method

ABSTRACT

A system and method for a valve system for downhole use with downhole tools such as packers is disclosed. The valve system includes an opening piston and a closing piston which preferably utilize any suitable means to control erosion such as, for example only, carbide inserts that define the various inlets and outlets of the opening and closing piston. Preferably a carbide baffle is used to produce a slower and smoother fluid pressure flow through the valve system. Pressure from the casing bore above a selected value causes opening piston to shift and permit fluid flow past the valve stem of the closing piston and into the filling port of the packer. When pressure inside the inflatable packer produces a force on the closing piston above a selected amount, the closing piston shifts to the closed position whereby fluid flow into or out of the inflatable packer is prevented. Once pressure is bled off the casing bore, the return spring of the opening piston pushes the piston back to seal off the port. A non-elastomeric seal such as a TEFLON seal and/or an elastomeric seal may be bonded to the closing piston is provided to resist forces that could otherwise damage the seal as the closing piston is shifted to the closed position. An equalizer valve is preferably built into the opening piston equalize hydrostatic pressure to the casing bore.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to downhole valves and,more particularly, to apparatus and methods for downhole valves usedwith downhole tools such as packers and plugs.

[0003] 2. Description of the Background

[0004] Downhole tools, such as packers, long seal packers, and the like,may be used within a wellbore for many purposes including cementingrelated operations. In such downhole tools, a valve assembly may be usedfor inflating or expanding a sealing element.

[0005] Depending on well operations and programs, fluids possiblyincluding abrasive fluids such as cement, maybe pumped through the valvesystem. However, the rapid flow of fluids and especially abrasive fluidsthrough the valving system may erode and therefore destroy the valveassembly used with downhole tools such as packers and plugs. It wouldtherefore be desirable to provide a valving system for a downhole toolthat somehow eliminates or reduces valve system erosion even whenabrasive fluids are involved.

[0006] High fluid flow through a valve system can cause othermalfunctions of various types. For instance, the valve system sequenceof operation may not respond as desired when the fluid flow input isvery high. It would be desirable to somehow provide a valve systemactuation logic that works reliably for a wide range of fluid flowrates, including pulses of high fluid flow and the like. Another exampleof valve malfunction caused by high fluid flow rates may occur when aseal on a piston or valve is moved past a port through which high fluidflow occurs, and the seal is damaged. There is a tendency for the sealto be damaged by cutting, wear, or being pulled off the seat surface forthe seal as the seal moves past the port.

[0007] Yet other problems with such valve assemblies relate to the factthat the internal packer elements are maintained dry or with littleinternal fluid to avoid the possibility of bulges caused by internalfluids that might be subject to friction with the casing and result inwear or tearing. However, problems may still occur. For instance, thehydrostatic pressure applied to the outside of the flexible sealingelement as the packer is run into the wellbore may act on the valveassembly and cause damage such as breaking shear pins, effecting somesealing against the mandrel, and/or otherwise preventing or inhibitinginflation of the packer.

[0008] U.S. Pat. No. 4,716,963, issued Jan. 5, 1988, to George et al.,discloses methods and apparatus for setting a packer and placing a sealassembly into the packer bore on a single trip into the borehole. Suchapparatus includes a releaseable mechanism coupling the seal assembly infixed relation to the packer until such time as the packer is at leastpartially set. Methods and apparatus include a mechanism forhydraulically setting a packer without any manipulation of the tubingstring. A pair of hydraulic pistons are utilized to move in oppositedirections and exert forces on both a packer actuating sleeve and thepacker body to set the packer. Methods and apparatus are provided foractuating well tools in response to the hydrostatic pressure in thewell. Through use of such apparatus, a chamber at atmospheric pressureis placed in communication with one side of a hydraulically moveablemember, the other side of which is exposed to hydrostatic pressure.

[0009] While the above patent relates to setting a packer, no teachingis provided for avoiding the erosion damage to downhole valves caused bycement or other fluid-induced abrasion. Moreover, the above prior artdoes not teach how to prevent damage caused to a seal caused when theseal moves by a port through which fluid flows at a high rate, forinstance to thereby close off the port. Consequently, it would bedesirable to provide means that limit damage to valves that may be inpackers, long packers, or other downhole tools. Those skilled in the arthave long sought and will appreciate the present invention whichprovides solutions to these and other problems.

SUMMARY OF THE INVENTION

[0010] The present invention was designed to provide an improved valvesystem for downhole tools.

[0011] Another object of the present invention is to provide a moredurable and reliable downhole valve system.

[0012] These and other objects, features, and advantages of the presentinvention will become apparent from the drawings, the descriptions givenherein, and the appended claims.

[0013] Therefore, the present invention provides for a valve system fora downhole tool comprising elements such as, for instance, a valve body,an opening valve assembly within the valve body, and an opening pistonfor the opening valve assembly wherein the opening piston may bemoveable in response to pressure acting thereon from a closed positionto an open position to permit fluid flow through a flow path through thevalve body. A closing valve assembly may also be provided within thevalve body. The flow path extends through the closing valve assemblywhen the opening piston is in the open position.

[0014] In a presently preferred embodiment, a sleeve surrounds theopening valve assembly. Moreover, the valve body preferably defines amachined aperture such that the sleeve slidably fits more precisely intothe aperture. As well, a sleeve preferably surrounds the closing valveassembly.

[0015] To limit rapid fluid flow, an impedance is provided to oppose orslow fluid flow. In a preferred embodiment, a baffle assembly isprovided which has a plurality of walls therein. Each of the pluralityof walls defines a one or more openings.

[0016] The valve system may preferably be configured so that the flowpath through the closing port extends around a closing piston valvestem. The closing piston is moveable to close the flow path if theinflated element is full and pressure acts on the end of the piston. Aseal may be bonded to the closing valve piston to prevent damage theretowhen the closing piston closes. In a preferred embodiment, the sealfurther comprises at least one non-elastomeric seal on the closingpiston.

[0017] A valve is provided to let pressure into the inflated element toequalize internal element pressure to the annulus pressure.

[0018] In operation, the method may comprise steps such as applyingpressure to an opening piston for moving the opening piston from anoriginal position to a shifted position to thereby open a flow paththrough the valve system for filling the inflatable element, andconnecting internal pressure from the inflatable element of the downholetool to a closing piston such that the closing piston moves from anoriginal position to a closed position after the internal pressurereaches a selected pressure. The movement of the closing piston maypreferably close the flow path to prevent further fluid flow into theinflatable element.

[0019] Other steps may include biasing the opening piston such that theopening piston moves back to the original position by reducing theapplied pressure, and locking the opening piston in the originalposition.

[0020] In a presently preferred embodiment, a step of shearing ashearable member occurs in response to the step of applying pressure topermit movement of the opening piston. Other steps may include impedingfluid flow into the fluid flow path with a baffle or providing that theflow path extends through the closing valve assembly such that after theopening piston moves, fluid flow occurs through the flow path into theinflatable element.

[0021] A method for making a valve system for a downhole tool with aninflatable element may comprise steps such as providing a valve bodywith a first cylinder for an opening piston wherein the opening pistonmay be moveable between an open position and a closed position forcontrolling fluid flow for the inflatable element. Other steps mayinclude providing the valve body with a second cylinder for a closingpiston such that the closing piston may be moveable between an openposition and a closed position for controlling fluid flow for theinflatable element, inserting a first cylinder liner in the valve bodyaround the opening piston, and inserting a second cylinder liner in thevalve body around the closing piston.

[0022] The method includes providing ports through the first cylinderliner and the second cylinder liner or machining the first cylinder andthe second cylinder in the valve body for receiving the first cylinderliner and the second cylinder liner, respectively.

[0023] In one embodiment of the present invention, the valve system forthe downhole tool may comprise elements such as, for instance, a valvebody having a fluid flow path therethrough, a valve assembly disposedwithin the valve body, and a baffle assembly for the valve body. Thebaffle assembly may comprise a plurality of walls spaced apart andsecured with respect to each other. The plurality of walls define one ormore ports. The baffle assembly receives fluid flow for the fluid flowpath for such purposes as limiting and/or impeding fluid flow and/orsmoothing fluid flow through he valve system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a perspective view, partially in section, of a valvesystem with insert sleeves shown in accord with the present invention;

[0025]FIG. 2 is a perspective view, partially in section, of the valvesystem of FIG. 1 in the initial installed valve position;

[0026]FIG. 3 is a perspective view, partially in section, of the valvesystem of FIG. 1 in the initial installed valve configuration;

[0027]FIG. 4 is a perspective view, partially in section, of the valvesystem in the inflating valve configuration;

[0028]FIG. 5 is a perspective view, partially in section, of the valvesystem in the closed and locked valve configuration;

[0029]FIG. 6 is a perspective view, partially in section, that shows anequalizer valve within the opening valve piston;

[0030]FIG. 7 is a schematic view showing a diagram for a bafflearrangement in accord with the present invention; and

[0031]FIG. 8 is an elevational view shown a packer set within thewellbore casing in accord with the present invention.

[0032] While the present invention will be described in connection withpresently preferred embodiments, it will be understood that it is notintended to limit the invention to those embodiments. On the contrary,it is intended to cover all alternatives, modifications, and equivalentsincluded within the spirit of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Referring now to the drawings and more specifically to FIG. 1through FIG. 6, there is shown a valve system 10 in accord with thepresent invention. As discussed in detail hereinafter, the valve systemof the present invention uses an improved actuation logic based on fluidmoving through an inlet, around a closing valve stem, and then exitingthrough an outlet instead of through the valve.

[0034] A typical packer arrangement, such as packer arrangement 11 isshown in FIG. 8 within wellbore 15 and may include slips 17 andexpandable member 19. Expandable member 19 may be expanded to set packerarrangement 11 within the casing, tubular string, and the like which maybe found within wellbore or tubular string 15 by means of fluid flowcontrolled by valve system 10. For instance packer 11 may provide a sealbetween tubular string 23 and outer tubular string 15 such as a casingstring.

[0035] In one aspect of the invention, there is preferably providedhardened insert sleeves 12 to thereby protect valve body 14, shown splitfor convenience in viewing, from erosion due to fluid abrasion as shownin FIG. 1. In FIG. 2 and FIG. 3, valve assemblies 18 and 20 are shownwith insert sleeves 12 and 13 cut away. Insert sleeves 12 and 13 fitinto valve body cylinders 16 and 21, respectively. Valve body cylinders16 and 21 are preferably machined into valve body 14 to provide for aclose tolerance fit. Another advantage of insert sleeves 12 and 13 isthat they may conveniently be used to control port size, cross portlocation, and port finish quality in a manner that is much lessexpensive than attempting to machine valve body 14 to provide thisfunction. The various ports are discussed subsequently. Valve assembly18 is the opening valve and valve assembly 20 is the closing valve.Valve assemblies 18 and 20 preferably utilize carbides or hardened steelor other suitable erosion resisting materials to provide pistoncomponents with minimized wear due to abrasion. Screw members 22 and 24may be threaded into valve body 14 not further than the depth providedby shoulders 26 and 28, respectively. Preferably snap-on retainer rings30 and 32 mounted to screw members 22 and 24 and shim members 31 and 33may then be used to properly position the relative spacing of thecomponents within valve assemblies 18 and 20 and also with respect tovalve body 14. Spring 35 is preferably a stainless steel garter springused to provide bias to thereby lock the opening piston in a sealedposition as discussed subsequently. Shear pins 34 and 36 secure thevalve components in position after assembly and during running of thedownhole tool into the wellbore. In one embodiment, shear pins 34 and36, or breakable plugs, screws, or other breakable elements may beselectively broken within a desired operating sequence to effectoperation of valve system 10 as discussed subsequently. Other pressureoperated means could be used that effectively are actuated in responseto pressure that increases above a selected level.

[0036] Fluid controlled by opening valve 18 enters through port 38. In apreferred embodiment fluid control is provided before fluid reaches port38 in a unique manner by use of a baffle arrangement, such as bafflearrangement 40 shown conceptually in FIG. 7. Baffle arrangement 40 maypreferably include up to three or more wall members, such as wallmembers 42, 44, and 46 with openings or holes staggered relative to eachstacked member such that slurry or cement flow into opening valve 18through port 38 is retarded, restricted, or impeded to slow fluid flowtherethrough and so prevent or reduce erosion. Thus, ports 48, 50, and52 may be staggered with respect to each other to thereby impede fluidflow. Flow into baffle 40 may be through port 53 whereupon flowcontinues through baffle 40 to exit baffle 40 through port 38 and intovalve assembly 10. Baffle arrangement 40 is preferably formedsubstantially or entirely with carbide components. Baffle 40 may beformed as part of valve housing 14, may be attached to valve housing, ormay be separated from valve housing 14 with a conduit leading thereto.

[0037] In the initial position, as per FIG. 1-FIG. 3, opening piston 54provides seals 58 and 60 that seal off filling fluid flow port 62. Seals58 and 60 may each comprise one or more seals, as desired. Note that thesize and shape of ends 64 and 66 of flow port 62 are defined by insertsleeves 12 and 13. As shown in FIG. 4, fluids pressure due to fluid flowthrough baffle 40 to inlet 38 acts on opening piston 54. As the pressureincreases, force applied to opening piston 54 overcomes return spring 56and to shear pin 34 such that opening piston pin 68 is freed to moveoutwardly after shear pin 34 breaks. In other words, pressure fromcasing bore 15 against sealed face area 70 of opening piston 54 producesforce up to the shear rating of shearing pin 34 installed in openingpiston pin 68. This allows opening piston 54 to shift, permittinginflation fluid flow through valve system 10 passing through valvesystem outlet port or fill port 74 and thus into expandable packerelement 19 (see also FIG. 8). Flow arrows 72 disclose the flow path.

[0038] It will be noted that fluid flow proceeds around closing valvestem 76 which is in the initial position during filling. Thus, fluidflow is directed around the initial position of closing valve stem 76rather than past seals or ports uncovered by closing valve assembly.Forces acting between seal 78 and seal 80 of closing stem 76 are equaland opposing so that premature closing of valve assembly 20 is preventedregardless of pressure acting along flow path 72 while fluid inflatesthe packer.

[0039] Pressure inside of packer 11 produces a force on sealed end facearea 84 of closing piston 86, by means of pressure at limit port 77which connects to the interior of inflatable element19. When thepressure at limit port 77 becomes equal to the shear rating of shearingpin 36 of closing piston pin 82, then closing piston 86 shifts into theclosed position indicated in FIG. 5. Thus, filling fluid flow passageway72 is blocked. As pressure is bled from casing bore 15, return spring 56pushes opening piston 54 back to seal off port 88. Piston lock 90 whichis activated by garter spring 35 may be used to prevent opening piston54 from opening again.

[0040] As closing piston 86 moves to the closed position, seal 80 ismoved by outlet port 74. Seal 80 is preferably a non-elastomeric seal,such as a Teflon seal or other non-elastomer. In a preferred embodiment,seal 80 is not bonded to the piston. However, seal 80 could be bonded toclosing piston 86 such as by glue, heating, or any other method ofbonding to thereby permanently affix seal 80 to closing piston 86 suchthat seal 80 cannot be removed or pulled off of closing piston 86, ifdesired. An elastomer O-ring seal would be subject to significant damageand possibly being torn off as the seal moves past outlet or fill port74. However in a preferred embodiment, an elastomer O-ring seal 81 mayalso be provided directly adjacent to seal 80 on piston 86. In apreferred embodiment, seal 81 maybe bonded in position by any suitablemeans. An elastomer O-ring seal 81 easily and conveniently forms a goodseal, but is subject to many problems such as abrasion, tearing,temperature and the like. While a non-elastomer or Teflon seal 80 isless subject to tearing, abrasion, temperature problems, is resistant toacidic and corrosive materials, and has other good properties, anon-elastomer or Teflon seal is more difficult to provide good sealing.Therefore, the combination seal arrangement of non-elastomer seal 80with an elastomer seal 81 may significantly improve both the sealing andthe reliability of the seal arrangement.

[0041]FIG. 6 shows equalizer valve 91 which may include ball 92, spring94, and seat 96. Hole 93 provides entry into opening piston 54.

[0042] Equalizer valve 91 may be positioned within opening piston 54 toform a flow passageway there through hole 97 into equalizer valve 91 outthrough hole 93 into fill port 74 to allow for hydrostatic pressureequalization inside the inflation element 19 of packer 11 to casing bore15.

[0043] Thus in summary of a presently preferred embodiment of theactuation logic of the present invention, to effect opening or settingof packer 11 pressure from casing bore 15 against sealed face area 70 ofopening piston 54 produces force up the shear rating of shearing pin 34installed in opening piston pin 68. Equal opposing force due to pressureon stem portion 76 of closing piston 86 prevents premature closing ofclosing piston 86 while fluid inflates inflatable element 19 of packer11. When pressure inside of inflatable element 19 produces a force onsealed end face area 84 of closing piston 86 due to the fluid connectionto internal element 19 with limiting port 77 that is equal to shearrating on pin 36 of closing piston pin 82, then closing piston 86 shiftsto the closed position as indicated in FIG. 5. When pressure is bledfrom casing bore 15, return spring 56 of opening piston 54 pushesopening piston 54 back to seal off port 88. Piston lock mechanism 90 nowlocks opening piston 54 in position to prevent opening piston 54 fromreopening.

[0044] The inserts and/or other valve components are preferably hardenedby any suitable means and may comprise hardened steel, carbide, one ormore hardened coatings, ceramic materials, and the like.

[0045] Therefore, the foregoing disclosure and description of theinvention is illustrative and explanatory thereof, and it will beappreciated by those skilled in the art, that various changes in thesize, shape and materials, the use of mechanical equivalents, as well asin the details of the illustrated construction or combinations offeatures of the various elements maybe made without departing from thespirit of the invention.

What is claimed is:
 1. A valve system for a downhole tool, comprising: avalve body; an opening valve assembly within said valve body, saidopening valve assembly having an opening piston, said opening pistonbeing moveable from a closed position to an open position in response topressure acting thereon to open a flow path through said valve body; anda closing valve assembly within said valve body, said flow pathextending through said closing valve assembly when said opening pistonis in said open position.
 2. The valve system of claim 1, furthercomprising: a sleeve surrounding said opening valve assembly.
 3. Thevalve system of claim 1, further comprising: said valve body defining amachined aperture, said sleeve slidably fitting into said aperture. 4.The valve system of claim 1, further comprising: a sleeve surroundingsaid closing valve assembly.
 5. The valve system of claim 1, furthercomprising: a baffle having a plurality of walls therein, each of saidplurality of walls defining a one or more openings.
 6. The valve systemof claim 1, wherein said flow path through said closing piston extendsaround a closing piston valve stem.
 7. The valve system of claim 1,wherein: said closing piston is moveable to close said flow path.
 8. Thevalve system of claim 1, further comprising a seal bonded to saidclosing piston.
 9. The valve system of claim 1, further comprising anon-elastomeric seal on said closing piston.
 10. The valve system ofclaim 1, further comprising an elastomeric seal on said closing pistonadjacent said non-elastomeric seal.
 11. The valve system of claim 1,further comprising: an equalizer valve mounted within said openingpiston.
 12. A method for a valve system for a downhole tool with aninflatable element, said method comprising: applying pressure to anopening piston for moving said opening piston from an original positionto a shifted position to thereby open a flow path through said valvesystem for filling said inflatable element; and connecting internalpressure from said inflatable element of said downhole tool to a closingpiston such that said closing piston moves from an original position toa closed position after said internal pressure reaches a selectedpressure, said movement of said closing piston closing said flow path toprevent further fluid flow into said inflatable element.
 13. The methodof claim 12, further comprising: biasing said opening piston such thatsaid opening piston moves back to said original position by reducingsaid applied pressure, and locking said opening piston in said originalposition.
 14. The method of claim 12, further comprising: shearing ashearable member in response to said step of applying pressure to permitmovement of said opening piston.
 15. The method of claim 12, furthercomprising: bonding a sealing element to said closing piston.
 16. Themethod of claim 12, further comprising: providing a non-elastomer as asealing element of said closing piston.
 17. The method of claim 12,further comprising: providing an elastomeric adjacent said non-elastomersealing element.
 18. The method of claim 12, further comprising:equalizing pressure inside said inflatable element to a wellbore. 19.The method of claim 12, further comprising: impeding fluid flow intosaid fluid flow path with a baffle.
 20. The method of claim 12, furthercomprising: providing said flow path through said closing valve assemblysuch that after said opening piston moves, then fluid flow occursthrough said flow path into said inflatable element.
 21. A method for avalve system for a downhole tool with an inflatable element, said methodcomprising: providing a valve body with a first cylinder for an openingpiston, said opening piston being moveable between an open position anda closed position for controlling fluid flow for said inflatableelement; providing said valve body with a second cylinder for a closingpiston, said closing piston being moveable between an open position anda closed position for controlling said fluid flow for said inflatableelement; inserting a first cylinder liner in said valve body around saidopening piston, and inserting a second cylinder liner in said valve bodyaround said closing piston.
 22. The method of claim 21, furthercomprising: providing ports through said first cylinder liner and saidsecond cylinder liner.
 23. The method of claim 21, further comprising:machining said first cylinder and said second cylinder in said valvebody for receiving said first cylinder liner and said second cylinderliner, respectively.
 24. The method of claim 21, further comprising:bonding a sealing element to said closing piston.
 25. The method ofclaim 21, further comprising: providing a non-elastomer as a sealingelement of said closing piston.
 26. The method of claim 21, furthercomprising: providing a plurality of walls with offset openingstherebetween for impeding said fluid flow into said valve body.
 27. Themethod of claim 21, further comprising: providing said flow path throughsaid closing valve assembly such that when said opening piston is insaid open position, then said fluid flow occurs through said flow pathinto said inflatable element.
 28. The method of claim 21, furthercomprising: providing a locking assembly for locking said openingposition in said closed position after said inflatable element isinflated.
 29. The method of claim 21, further comprising: forming aequalizing valve in said opening position to permit said fluid flowthrough said opening piston when said opening piston is in said closedposition.
 30. A valve system for a downhole tool, comprising: a valvebody, said valve body having a fluid flow path therethrough; a valveassembly disposed within said valve body; a baffle assembly for saidvalve body, said baffle assembly comprising a plurality of walls spacedapart and secured with respect to each other, said plurality of wallsdefining one or more ports, said baffle assembly receiving fluid flowfor said fluid flow path.
 31. The valve system of claim 30, wherein saidvalve assembly disposed within said valve body further comprises: anopening valve assembly within said valve body, said opening valveassembly having an opening piston, said opening piston being moveable inresponse to pressure acting thereon from a closed position to an openposition to open a flow path through said valve body; and a closingvalve assembly within said valve body, said flow path extending throughsaid closing valve assembly when said opening piston is in said openposition.
 32. The valve system of claim 31, further comprising: a sleevesurrounding at least one of said opening valve assembly or said closingvalve assembly.
 33. The valve system of claim 31, wherein said flow paththrough said closing piston extends around a closing piston valve stem.34. The valve system of claim 31, wherein: said closing piston ismoveable in response to pressure acting thereon to close said flow path.35. The valve system of claim 31, further comprising a seal bonded tosaid closing valve piston.
 36. The valve system of claim 31, furthercomprising a non-elastomeric seal on said closing piston.
 37. The valvesystem of claim 31, further comprising: an equalizing valve mountedwithin said opening piston.
 38. The valve system of claim 31, furthercomprising: said valve body defining a machined aperture, and a sleeveslidably fitting into said aperture.
 39. The valve system of claim 31,wherein said baffle assembly receives said fluid flow prior to saidfluid flow entering said fluid flow path through said valve body.
 40. Avalve system for a downhole tool controlling fluid flow to an expandablemember, comprising: a valve body; at least one valve assembly withinsaid valve body, said at least one valve assembly having at least onepiston; and at least one non-elastomer seal disposed on said at leastone piston.
 41. The valve system of claim 40, further comprising: anelastomer seal adjacent said non-elastomer seal.
 42. The valve system ofclaim 41, further comprising: at least one of said elastomer seal orsaid non-elastomer seal being bonded to said at least one piston. 43.The valve system of claim 40, further comprising: an opening valveassembly with an opening piston within said valve body, a closing valveassembly with a closing piston within said valve body, saidnon-elastomer seal being provided on said closing piston.
 44. The valvesystem of claim 43, further comprising: said flow path extending throughsaid closing valve assembly when said opening piston is in said openposition.
 45. The valve system of claim 44, further comprising hardenedsleeves insertable into said valve body to resist erosion due to saidfluid flow.
 46. The valve system of claim 44, wherein said opening valveassembly and said closing valve assembly are hardened to resist erosiondue to said fluid flow.